Method for cutting to length a piece of tube from a tube

ABSTRACT

A method for cutting to length a piece of tube having an inner tube and an outer tube sheathing, the piece of tube being detached with the aid of a cutting tool at a cutting site in a plane oriented transversely to the longitudinal extent of the tube. The tube sheathing is surrounded by a severable tube fixing element, which covers over the intended cutting site before the piece of tube is detached using the cutting tool at the cutting site, and the tube fixing element completely encloses the outer tube sheathing in the circumferential direction. The tube fixing element is fixed on the tube sheathing and/or the tube enclosed by the tube fixing element is severed with the cutting tool such that a relative displacement of the tube fixing element with respect to the tube sheathing or of the tube sheathing with respect to the inner tube is prevented.

INCORPORATION BY REFERENCE

The present application is a continuation of U.S. patent applicationSer. No. 13/597,731, filed Aug. 29, 2012, the entire contents of whichare incorporated by reference herein as if fully set forth.

BACKGROUND

The invention relates to a method for cutting to length a piece of tubefrom a tube, which tube has an inner tube and an outer tube sheathing,enclosing the inner tube, the piece of tube being detached from the tubewith the aid of a cutting tool at a cutting site in a cutting planeoriented transversely to the longitudinal extent of said tube, the tubesheathing of the tube being surrounded by a severable tube fixingelement, which covers over the intended cutting site before the piece oftube is detached from the tube with the aid of the cutting tool at thecutting site, and the tube fixing element completely enclosing the outertube sheathing in the circumferential direction.

US 2008/0016936 A1 already discloses a method of the type mentioned atthe beginning which is used for cutting to length a piece of tube from atube that has an inner tube and an outer tube sheathing, which enclosesthe inner tube and is formed as a braiding of metal or plasticfilaments. To be able to detach the piece of tube from the tube with theaid of a cutting tool at a cutting site in a cutting plane orientedtransversely to the longitudinal extent of the tube, the previouslyknown method envisages surrounding the tube sheathing of the tube by aseverable tube fixing element, which covers over the intended cuttingsite before the piece of tube is detached from the tube with the aid ofthe cutting tool at the cutting site. Although the previously knownmethod prevents individual metal or plastic filaments of the braidingthat is provided as the tube sheathing from being able to snag when itis intended to push a clamping sleeve onto the piece of tube cut tolength in this way, these clamping sleeves usually have a clampingsleeve inner diameter that is adapted in comparison with the outerdiameter of the piece of tube in such a way that, when the clampingsleeve is pushed on, there is the risk of the tube fixing element beingpushed back with respect to the tube sheathing and, in addition orinstead of that, the tube sheathing being pushed back with respect tothe inner tube, whereby in turn the clamping sleeve is not heldsufficiently securely and firmly on the corresponding end of the pieceof tube. If, on the other hand, the clamping sleeve is produced with asignificantly greater inner diameter in comparison with the outerdiameter of the tube braiding, in order to achieve a large radialdistance between these two parts in the undeformed state and avoid acollision of the ends of the braiding with the clamping sleeve duringthe pushing-on operation, this large radial distance has disadvantageouseffects in the subsequent crimping operation.

SUMMARY

There is therefore particularly the objective of improving the methodmentioned at the beginning in such a way as to minimize the risk of thetube fixing element being displaced with respect to the tube sheathingor the tube sheathing being displaced with respect to the inner tubewhen a piece of tube is pushed on.

To meet this objective, it is provided by the invention, in the case ofthe method mentioned at the beginning, that the tube fixing element isfixed on the tube sheathing and/or the tube enclosed by the tube fixingelement is severed with the aid of the cutting tool in such a way that arelative displacement of the tube fixing element with respect to thetube sheathing or of the tube sheathing with respect to the inner tubeis prevented.

Also in the case of the method according to the invention, beforecutting to length a piece of tube, the tube sheathing is surrounded by aseverable tube fixing element which covers over the intended cuttingsite before the piece of tube is severed from the tube with the aid ofthe cutting tool at the cutting site. The method according to theinvention provides here that the tube fixing element completely enclosesthe outer tube sheathing in the circumferential direction, andconsequently the tube sheathing covers over or wraps around at least360° of the circumference. In this case, the tube fixing element isfixed on the tube sheathing and/or the tube enclosed by the tube fixingelement is severed with the aid of a cutting tool in such a way that arelative displacement of the tube fixing element with respect to thetube sheathing or of the tube sheathing with respect to the inner tubeis prevented.

A particularly simple procedure which makes it considerably easier toapply such a tube fixing element to a tube provides that the tube fixingelement is a single-sided adhesive tape.

At the same time, a variant of the method according to the inventionprovides that the tube fixing element formed as adhesive tape has amiddle piece which completely encloses the tube and is adjoined on bothsides by tube-fixing-element end pieces, that the tube-fixing-elementend pieces lie with their adhesive surfaces against one another, andthat the tube-fixing-element end pieces that are lying with theiradhesive surfaces against one another are placed against the tube insuch a way that the adhesive surface of one of the tube-fixing-elementend pieces is adhesively held on the tube or on the piece of tube by apartial region extending over the other tube-fixing-element end piece.

A further embodiment according to the invention provides that the tubefixing element formed as adhesive tape has two tube-fixing-elementpartial regions, which are connected to one another and of which onetube-fixing-element partial region completely encloses the tube and ofwhich the other tube-fixing-element partial region is adhesively heldwith its adhesive surface on the outer side of the tube-fixing-elementpartial region enclosing the tube. This embodiment according to theinvention offers the advantage that the tube fixing element protrudesonly a little beyond the outer diameter of the tube sheathing.

A development of the method according to the invention is provided inthat the tube fixing element is a shrink tube, the clear tube diameterof which can be reduced by exposure to heat in such a way that theshrink tube lies immovably against the tube outer circumference and inparticular against the tube sheathing of the tube. Such a shrink tubemay also be formed as a band of plastic running endlessly around andcompletely enclosing the tube sheathing. When the shrink tube is exposedto heat, its clear tube diameter is reduced in such a way that theshrink tube comes to lie taut against the tube sheathing. At the sametime, however, the tube sheathing is thereby also pressed onto the innertube in such a way that a displacement of the tube fixing element withrespect to the tube sheathing and of the tube sheathing with respect tothe inner tube is prevented.

In the case of longer pieces of tube, onto which a shrink tube canpossibly only be pushed and positioned with difficulty, a simple andadvantageous variant of the method according to the invention providesthat the tube fixing element is formed in an injection-molding processas a surround that completely encloses the tube sheathing in thecircumferential direction in a partial portion.

To avoid undesired transverse forces when cutting to length the piece oftube that could bring about a displacement of the tube fixing elementwith respect to the tube sheathing or even of the tube sheathing withrespect to the inner tube at least in the axial direction, an embodimentaccording to the invention that represents a development provides thatthe tube is cut to length by a cutting blade that serves as a cuttingtool and is guided approximately perpendicularly to the longitudinaldirection of the tube. With the aid of such a cutting blade guidedapproximately perpendicularly to the longitudinal direction of the tube,the piece of tube can be cut to length from the tube at the desiredcutting site.

It is also possible, however, for the tube to be cut to length by acutting tool that develops a cutting heat, to be precise preferably insuch a way that the plastics material that becomes pasty while exposedto the cutting heat adhesively bonds, fuses or similarly fixes at leastone of the component parts: the tube fixing element, tube sheathing orinner tube, at least in certain regions to at least one of the adjacentcomponent parts, in order to secure the relative position between thetube sheathing and the inner tube. If a tube sheathing produced forexample from plastic filaments is cut to length with such a cutting tooldeveloping cutting heat, the plastics material of the plastic filamentsthat becomes pasty due to the cutting heat can adhesively bond or fuseto the tube sheathing and/or the inner tube in such a way that arelative displacement of these component parts at least in the axialdirection is avoided.

A preferred embodiment according to the invention provides that aclamping sleeve, a crimping sleeve or a sleeve-shaped tube end piece ispushed onto the end of the piece of tube that is secured with the aid ofthe tube fixing element and that the tube fixing element projects overthe inner end of the clamping sleeve, crimping sleeve or the tube endpiece and forms an anti-kink device.

BRIEF DESCRIPTION OF THE DRAWINGS

Developments according to the invention are provided by the figures inconjunction with the claims and the description. The invention isdescribed in more detail below on the basis of preferred exemplaryembodiments.

In the figures:

FIGS. 1 to 4 show individual method steps of a method intended forcutting to length a piece of tube, a tube fixing element formed as anadhesive tape being applied to the tube that is to be cut to length andhaving a middle piece which completely encloses the tube and is adjoinedon both sides by tube-fixing-element end pieces,

FIGS. 5 to 8 show method steps of a method likewise intended for cuttingto length a piece of tube, a tube fixing element formed as an adhesivetape being applied to the tube that is to be cut to length and havingtwo tube-fixing-element partial regions, of which onetube-fixing-element partial region completely encloses the tube and ofwhich the other tube-fixing-element partial region is adhesively heldwith its adhesive surface on the outer side of the tube-fixing-elementpartial region enclosing the tube,

FIGS. 9 to 11 show method steps for cutting to length a piece of tube, ashrink tube being applied as a tube fixing element to the tube that isto be cut to length, which shrink tube can be reduced in its clear tubediameter by exposure to heat in such a way that t he shrink tube comesto lies immovably against the tube sheathing,

FIGS. 12 and 13 show tube fixing element projecting over a tube endpiece and serving as an anti-kink device, in a side view (FIG. 12) and aperspective representation (FIG. 13),

FIGS. 14 and 15 show the method steps intended for cutting to length apiece of tube, a guillotine-like cutting tool being used here, guidedapproximately perpendicularly to the longitudinal direction of the tubeduring the cutting operation,

FIGS. 16 and 17 show the method steps intended for cutting to length apiece of tube, the tube being cut to length here with a cutting toolthat develops a cutting heat, and

FIG. 18 shows a tube prepared for cutting to length a piece of tube, anovermolding of the tube that completely surrounds the tube in thecircumferential direction in a partial portion being formed in theregion of the intended cutting site.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Various variants of a method according to the invention that is intendedfor cutting to length a piece of tube 1 from a flexible tube arepresented in FIGS. 1 to 18. The tube used for the piece of tube 1 has aninner tube 2 and an outer tube sheathing 3, enclosing the inner tube 2.The tube sheathing 3 is formed here as a braiding, which is produced byinterwoven metal or plastic filaments. It is also possible to use ahybrid braiding, the braiding filaments of which consist partly ofplastic and partly of metal.

The piece of tube 1, which is required for example for producing aflexible sanitary tube line, is detached from the tube with the aid of acutting tool at a cutting site in a cutting plane oriented transverselyto the longitudinal extent of said tube. For this purpose, the tubesheathing 3 is surrounded by a severable tube fixing element 4, whichcovers over the intended cutting site before the piece of tube 1 isdetached from the tube with the aid of the cutting tool at the cuttingsite.

Sanitary tube lines usually have on both end faces a sleeve-shaped tubeend piece 5, formed for example as a clamping or crimping sleeve (cf.FIGS. 12 and 13). Since the clear sleeve inner diameter of such a tubeend piece 5 corresponds more or less approximately to the outer diameterof the tube sheathing 3, particularly provided with a tube fixingelement 4, there is the problem of minimizing the risk of the tubefixing element 4 being displaced with respect to the tube sheathing 3 orthe tube sheathing 3 being displaced with respect to the inner tube 2when a tube end piece 5 is pushed on.

To solve this problem, it is provided in the case of the method variantsrepresented here that the tube fixing element 5 completely encloses andis fixed on the outer tube sheathing 3 in the circumferential directionand/or the tube enclosed by the tube fixing element 4 is severed withthe aid of the cutting tool in such a way that a relative displacementof the tube fixing element 4 with respect to the tube sheathing 3 or ofthe tube sheathing 3 with respect to the inner tube 2 is prevented.

In FIGS. 1 to 4 on the one hand and FIGS. 5 to 8 on the other hand, twovariants of such a method in which the tube fixing element 4 is formedby a single-sided adhesive tape are illustrated. An adhesive tapeserving as a tube fixing element 4 can be positioned and applied atalmost any location of a tube, which may even be long. In addition, asingle-sided adhesive tape has the advantage that the adhesive tape canbe drawn firmly onto the tube in such a way that the adhesive tapeserving as the tube fixing element 4 is fixed on the tube sheathing 3and the tube sheathing 3 is fixed on the inner tube 2 and anunintentional relative displacement of these component parts 2, 3 and 4is prevented.

In the case of the procedures that are shown in FIGS. 1 to 4, the tubefixing element 4 formed as adhesive tape has a middle piece 6, whichcompletely encloses the tube and is adjoined on both sides bytube-fixing-element end pieces 7, 8. These tube-fixing-element endpieces 7, 8 lie with their adhesive surfaces 9 against one another, thetube-fixing-element end pieces 7, 8 that are lying with their adhesivesurfaces 9 against one another being placed against the tube in such away that the adhesive surface 9 of one of the tube-fixing-element endpieces 7, 8 is adhesively held on the tube or on the piece of tube 1 bya partial region extending over the other tube-fixing-element end piece8, 7.

Since it is thereby ensured that the tube-fixing-element end pieces 7, 8do not disruptively protrude beyond the tube, the tube end piece 5 caneasily be pushed over the extreme end of a tube.

By contrast, the procedure shown in FIGS. 5 to 8 has twotube-fixing-element partial regions 10, 11, which are connected to oneanother and of which one tube-fixing-element partial region 10completely encloses the tube and of which the other tube-fixing-elementpartial region 11 is adhesively held with its adhesive surface 9 on theouter side of the tube-fixing-element partial region 10 enclosing thetube. In the case of this procedure, the tube fixing element 4 scarcelyprotrudes beyond the outer diameter of the tube sheathing 3, so thathere a sleeve-shaped tube end piece 5 can be easily pushed on.

In FIGS. 9 to 11 there is illustrated a method variant in which a shrinktube serves as the tube fixing element 4. Although the shrink tube isrepresented in FIGS. 9 to 11 as a strip of material cut to length onboth sides and the strip ends of which are adhesively attached to oneanother by exposure to heat, this shrink tube is usually an endlessnarrow band of material, the clear tube diameter of which can be reducedby exposure to heat in such a way that the shrink tube lies immovablyagainst the tube outer circumference and in particular against the tubesheathing 3 of the tube.

In FIGS. 12 and 13 it is intended to illustrate that the width of thetube fixing element 4 in the longitudinal direction of the tube may bedimensioned such that the tube fixing element 4 projecting over theinner end of the tube end piece 5 forms an anti-kink device.

In FIGS. 14 to 17 it is shown that the tube completely enclosed by thetube fixing element 4 can be severed with the aid of the cutting tool insuch a way that a relative displacement of the tube fixing element 4with respect to the tube sheathing 3 or of the tube sheathing 3 withrespect to the inner tube 2 is prevented. In FIGS. 14 and 15 it isprovided for this purpose that the tube is cut to length with a cuttingblade 12 that serves as a cutting tool and is guided approximatelyperpendicularly to the longitudinal axis of the tube.

In the case of the exemplary embodiment illustrated in FIGS. 16 and 17,the tube is cut to length with a cutting tool 13 that develops a cuttingheat, to be precise in such a way that the plastics material thatbecomes pasty while exposed to the cutting heat adhesively bonds orfuses at least one of the component parts: the tube fixing element 4,tube sheathing 3 or inner tube 2, at least in certain regions to atleast one of the adjacent component parts 2, 3, 4. Instead of thecutting tool 13, formed here in the manner of a soldering iron, a laserapparatus with a laser beam, that likewise develops a cutting heat, mayoptionally be used.

In FIG. 18 it is shown that the tube fixing element 4 may also be formedby an injection-molding process as a tube surround that completelyencloses the tube sheathing 3 in the circumferential direction in apartial portion.

Irrespective of whether adhesive tape, a shrink tube or a tube surroundproduced by an injection-molding process is used for the tube fixingelement 4, it is expedient if the tube fixing element has a smallthickness, and preferably a thickness of 0.5/100 ths to 8/100 ths of amm.

The invention claimed is:
 1. A method for cutting to length a piece oftube (1) from a tube, the tube having an inner tube (2) and an outertube sheathing (3), enclosing the inner tube (2), the method comprising:detaching the piece of tube (1) from the tube with a cutting tool at acutting site in a cutting plane oriented transversely to a longitudinalextent of said tube, surrounding the tube sheathing (3) of the tube witha severable tube fixing element (4), which is a single-sided adhesivetape that covers over an intended cutting site before the piece of tube(1) is detached from the tube with the cutting tool at the cutting site,with the tube fixing element (4) completely enclosing the outer tubesheathing (3) in a circumferential direction, wherein the tube fixingelement (4), fixed on the tube sheathing (3), and the tube are severedby the cutting tool in such a way that a relative displacement of thetube fixing element (4) with respect to the tube sheathing (3) or of thetube sheathing (3) with respect to the inner tube (2) is prevented andwherein the tube fixing element (4), formed as the single-sided adhesivetape, has a middle piece (6), which completely encloses the tube and isadjoined on both sides by tube-fixing-element end pieces (7, 8), thetube-fixing-element end pieces (7, 8) lie with adhesive surfaces (9)thereof against one another and the tube-fixing-element end pieces (7,8) that are lying with the adhesive surfaces (9) against one another areplaced against the tube in such a way that the adhesive surface (9) ofone of the tube-fixing-element end pieces (7, 8) is adhesively held onthe tube or on the piece of tube by a partial region extending over theother tube-fixing-element end piece (8, 7).
 2. The method as claimed inclaim 1, further comprising cutting the tube to length with a cuttingblade (12) that serves as a cutting tool and is guided approximatelyperpendicularly to the longitudinal direction of the tube.
 3. The methodas claimed in claim 1, wherein a clamping sleeve, a crimping sleeve ortube end piece (5) is pushed onto an end of the piece of tube (1) thatis secured with the aid of the tube fixing element (4) and the tubefixing element (4) projects over an inner end of the tube end piece (5)and forms an anti-kink device.
 4. The method as claimed in claim 1,further comprising cutting the tube to length with a cutting tool (13)that develops a cutting heat such that a plastic material of at leastone of the tube sheathing or the tube fixing element that becomes pastywhile exposed to the cutting heat fixes at least one of the componentparts: the tube fixing element (4), tube sheathing (3) or inner tube(2), at least in certain regions to at least one of the adjacentcomponent parts (2, 3, 4).